Ideal metal-decorated three dimensional covalent organic frameworks for reversible hydrogen storage

The most stable H-2 adsorption on pure covalent organic frameworks (COFs) occurs near O atoms, but its binding energy (similar to 0.05 eV) is not sufficient to satisfy the minimum value (0.24 eV) required for practical applications. Meanwhile, Li and Mg ion-decorated COFs have hydrogen adsorption energies of 0.28 and 0.30 eV, respectively, and their saturated hydrogen storage capacities exceed the DOE target (6.5 wt %). Also the effect of some counterions on hydrogen storage has been explored. Moreover, doped ions prefer to exist as isolated elements on COFs, which is another advantage to realize hydrogen storage media. (c) 2008 American Institute of Physics.